Amidine salts of aminobenzoic acids



Patented Sept. 23, 1941 AMIDINE SALTS or AMINOBENZOIC ACIDS I GarnetPhilip Ham, Old Greenwich, Conn., as-

signor to American Cyanamid Company, New- York, N. Y., a corporation ofMaine No Drawing.

Application September 28, 1939,

Serial No. 296,916

Claims.

This invention relates to amidine salts of aminobenzoic acids such asanthranilic acid and metaand para-aminobenzoic acids and to methods ofpreparing the same. I have found that certain well-defined amidine saltsof these aminobenzoic acids can be formed, which salts have unusualproperties of considerable commercial importance. They exert aremarkable stabilizing action on photographic developing solutions whenincorporated therein.

The amidines which I have found to form salts with aminobenzoic acidsmay be defined as amino-amidines; that is to say, amidines in which thealkyl or aryl group has been replaced by an amino or substituted aminogroup. The compounds may therefore be represented by the type formula IR RzN C INR3 in which R1, R2 and R3 are members of the group consistingof hydrogen, alkyl, hydroxyalkyl and aryl radicals and X is a member ofthe group consisting of R1,

OzNRrRz and The substituents R1, R2 and R3 may be the same or differentin various compounds included within the scope of the invention and itshould be understood that each symbol is intended to represent anymember of the group defined.

The amidine salts represented by the above type formula are trueaddition products; that is to say, the carboxylic acid group adds on tothe organic base to form a salt. I believe that this addition takesplace at one of the nitrogen atoms of the amidine, which undergoes achange of valence of from 3 to 5, but this fact has not as yet beendefinitely established for any of the salts of organic nitrogen bases.Accordingly, the above formula represents the customary method ofdesignating addition products of this nature, this method consistingsimply in showing the formula of the base in juxtaposition to theformula of the acid.

An inspection of the above type formula will show that the amidine saltsof my invention are salts of guanidine and its derivatives andsubstitution products, and particularly guanidine itself, guanylurea,biguanide, and their alkyl, hy-

droxyalkyl and aryl substitution products. These compounds are allorganic bases, and are sufficiently basic to enable them to form saltswith aminobenzoic acids such as anthranilic acid.

Any guanidine base may be used for this purpose, such as guanidineitself, dimethyl or trimethyl guanidine, dibutyl guanidine, mono-, diortriphenyl guanidine, ditolyl guanidlne, or alkoxy substituted guanidinessuch as mono-, dior triethanol guanidine and the like. Similarly, suchguanylurea compounds as guanylurea itself, monoor dimethyl guanylurea,diphenyl guanylurea, tetraethyl guanylurea, and triethanol guanylureaare organic bases which will form salts of anthranilic acid and metaandparaaminobenzoic acids.

Biguanide and such substituted biguanides as monoand dimethyl anddiethyl biguanides, diamyl biguanide, 1.5 diallyl biguanide, 1.1.5.5tetramethyl biguanide, 1.1.2 trimethyl biguanide and 1.2.3 triphenylbiguanide will also form salts of aminobenzoic acids in accordance withthemvention. It should be noted however that the biguanides, as well asthe other amidine bases included in the invention, will form bothneutral and acid salts with 'dibasic mineral acids such as sulfuricacid. These two classes of salts will, in turn, form salts containingone and two molecular equivalents of anthranilic acid for each mole ofthe biguanide or other amidine compound respectively. It should .be'understood that both classes of salts are included in the invention.

Many of the salts of my invention may be prepared by simply mixing asolution containing the free amidine base or its carbonate with asolution of aminobenzoic acid such as an anthranilic acid solution. Inmany cases it is convenient to start with the amidine sulfate,hydrochloride or other mineral .acid salt, from which the free base canbe liberated by dissolving in alcohol, addition of an alkali such assodium hydroxide, and removal of the precipitated sodium sulfate, sodiumchloride or other salt.

The invention will be illustrated in greater detail by the followingspecific examples. It should be understood however that although theseexamples describe certain compounds constituting specific embodiments ofthe invention they are given primarily for purposes of illustration andthe invention in its broader aspects is not limited thereto.

Example 1 164 parts of 98.2% guanidine carbonate are dissolved in partsof warm water and the C. and filtered,

The residue is dissolved in 125 parts of hot 1 water, cooled to about 25C. and the crystals are l filtered off and dried at room temperature.The 3 product'is guanidine tinthranilate, a. light-grey crystalline saltconsisting of stout bevelled prisms of parallel extinction. The index ofrefraction parallel to length is about 1.514; across the: f 1 length itis about 1.648. On long and continued 1 exposure to light the crystalsbecome slightly ;yellow. 1

1 1 The molecular weight of the new salt i s 2f14=; 3 It melts at 65-66C.', and is soluble in' water to' the extent of 133 g. per 100 g.ofwater at 25 C. 3 A 1 g. solution in 100 cc. of water exhibitsa pH 5 at25 C. of 5.93 and a potential of +0.07 yolt 1 Its analysis is shown inthe following table:

. Percentage Component V Theor. Det.

Carbon (0) Hydrogen (H) 'lFrom Lthe analysis and. molecular weight it isQe vident that the empirical formula of the compOIllIld isCN3H5.HOOC.C6H.NH2.H20.

Upon substituting for the guanidine equivalent solublefiinwater than isthe extremelysoluble fglu'anidine a nthranilate, but they are more'soluble iin organicl' solvents fsu ch' asfetha'nol, solvent Tnaphth'a nthe use. The diphenyl anddixylyl 'guanidinejlanthranilates were found tobe effecjt ve as r'nothproofingagents when prepared as a'gffl'fisolutign in solvent naphtha.

Example 2 parts byweightof 'biguanide sulfate were dispersed in 400parts byvolume of ethyl alcohol, 3:32 'parts;by -weight ofsodiumhydroxide were added andsthe mixture stirred for about 6 hours i toinsure 1 complete. reaction. The precipitate of sodiumsulfate. was thenfiltered off, leaving a solutioniof free biguanide in alcohol. {solutionthere was added with stirring 54.8 parts To this :ofvC. P. anthranilicacid, whereupon heat was generated.and a clear solution was obtained.QiUp'on standing, crystals of biguanide anthranilate separated out, .Themixturewas then stirred,

jfiltered, and the crystalswere washed with ethyl alcohol and driedunder a vacuum.

Biguanide anthranilate is a. white crystalline -:sa1t consisting of'thinplates; sometimes octag- The index of refraction parallel to cates thatthe crystals are anhydrous. Its analysis is shown in th following table:

145.2 parts by weight of guanylurea sulfate were dispersed -inYflOOparts by volume of ethyl alcohol. 16 parts by weight of sodium hydroxidewere added and the mixture stirred for four hoursto insure completereaction of the guanylurea sulfate. The precipitate of sodium sulfatewas then filtered off.

54.8 parts by weight of C. P. anthranilic acid were'added to thefiltrate with continuous agitation. The mixture wasthen stirred for onehour, the solids filtered off and Washed with ethyl alcohol, and theresulting crystals dried in 'vacuo for aboutten hours.

.Guanylurea,anthranilateis a white crystalline salt consisting oflongslender prisms of parallel extinction. The index of refractionparallel to the length is about 1.535; across the length it is about1.697. The crystals become slightly yellow upon long and continuedexposure to light. They melt at. 159-160 C. and are soluble in water tothe extent of 2.3 g. per cc. at 25 C. A1% solution in water exhibits at25 C. a pH of 6.43 and a potentialrof +0.07 volt. The molecular weightis 239, which indicates that the crystals are anhydrous. The analysis ofthe product is shown in the following table:

What I claim is: 1. Salts of aminobenzoic acids of the formula RlRzNcams .HOOC.CH4.NH2

in which R1, R2 and R3 are members of the group consisting of hydrogen,alkyl, hydroxyalkyl and aryl radicals and X is. a member of the groupconsisting of R1, 7

and

RENINRlR? 2. Salts of aminobenzoic acids of the formula lRaN CzNRa 11000I HN' HIN aryl radicals and X is a member of the group consisting of R1,

I RsNiCNRqRz 3. Salts of aminobenzoic acids of the formula RiRzN RiRnNin which R1, R2 and R3 are members of the group consisting of hydrogen,alkyl, hydroxyalkyl and aryl radicals.

4. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 aremembers of the group consistin of hydrogen, alkyl, hydroxyalkyl and arylradicals.

' 5. Salts of aminobenzoic acids of the formula in which R1, R2 and R3are members of the group consisting of hydrogen, alkyl, hydroxyalkyl andaryl radicals.

6. Salts of aminobenzoic acids of the formula HIN C l ZN in which R1, R2and R3 are members of the group consisting of hydrogen, alkyl,hydroxyalkyl and aryl radicals.

7. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 aremembers of the group consisting of hydrogen, alkyl, hydroxyalkyl andaryl radicals.

8. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 aremembers of the group consisting of hydrogen, alkyl, hydroxyalkyl andaryl radicals and X is a member of the group consisting of R1,

I O I CNR1R2 and RsN: CNRlRz with a solution of an aminobenzoic acid andseparating the resulting compound from the solvent.

GARNET PHILIP HAM.

